Again, they have a court approved document. As per the lawsuit filing:

Recognizing the value of Wiwynn’s custom-tailored solutions, on September 24, 2014, X Corp. entered into a Master Purchase Agreement with Wiwynn. For nearly eight years, X Corp. sourced and Wiwynn provided unique, custom-designed IT infrastructure products including rack solutions for X Corp.’s data centers, based on forecasts provided by X Corp. The components used to build the products are largely unique to the products, resulting in long lead times for ordering such component parts from suppliers. To ensure that products could be manufactured on the strict timeline X Corp. required, X Corp. specifically gave written approval for Wiwynn to purchase the necessary components to manufacture the custom products being made for X Corp., and expressly assumed liability for the procurement costs.

And a master purchase agreement is a legally binding contract.